<!DOCTYPE html>
<html lang="en" dir="ltr" class="client-nojs">
<head>
<meta charset="UTF-8" />
<title>Control points - PanoTools.org Wiki</title>
<meta http-equiv="X-UA-Compatible" content="IE=EDGE" />
<meta name="generator" content="MediaWiki 1.23.6" />






<style media="screen" type="text/css" title="Screen style sheet"> @import url(manual.css); </style>

<style>a:lang(ar),a:lang(kk-arab),a:lang(mzn),a:lang(ps),a:lang(ur){text-decoration:none}
/* cache key: panotools_wiki:resourceloader:filter:minify-css:7:90730a7865ba4b50e0b837e1821ff0a3 */</style>



<!--[if lt IE 7]><style type="text/css">body{behavior:url("/skins/vector/csshover.min.htc")}</style><![endif]--></head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-Control_points skin-vector action-view vector-animateLayout">
		
		
		<div id="content" class="mw-body" role="main">
			<a id="top"></a>
			
						<h1 id="firstHeading" class="firstHeading" lang="en"><span dir="auto">Control points</span></h1>
						<div id="bodyContent">
								<div id="siteSub">From PanoTools.org Wiki</div>
								
												
				<div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><p><br />
Most techniques for aligning photographs involve <b>Control points</b> at some stage.
</p><p>The principle is that by identifying the same physical features (a door, a tree, whatever) in
more than one photo, it is possible to establish facts about the relative camera orientations
mathematically.  The <a href="Pano12.html" title="Pano12">pano12</a> library contains a program called <a href="PTOptimizer.html" title="PTOptimizer">PTOptimizer</a> that does this job.
</p><p>Each of these real-world features is defined as a <i>pair</i> of control points.  Usually two
<i>pairs</i> of control points are sufficient to simply align one photograph against another, and
more photographs require more <i>pairs</i> - This alignment process is called <i>control point optimisation</i>.
</p><p>As well as adjusting this <a href="Roll.html" title="Roll">roll</a>, <a href="Pitch.html" title="Pitch">pitch</a> &amp; <a href="Yaw.html" title="Yaw">yaw</a> orientation, often
<a href="Field_of_View.html" title="Field of View">Field of View</a> and other aspects of the <a href="Lens_correction_model.html" title="Lens correction model">lens correction model</a> are <i>optimised</i> at the same
time.
</p><p>Control points can be picked manually by clicking with a mouse, and there are a number of
GUI front-ends<a class="external" href="http://wiki.panotools.org/GUI_front-ends">[*]</a> to help you do this.  There are other tools such as <a href="Autopano-sift.html" title="Autopano-sift">autopano-sift</a> and
<a href="Autopano.html" title="Autopano">autopano</a> that can generate control points automatically with some limitations.
</p><p>In addition to these simple control points, <a href="PTOptimizer.html" title="PTOptimizer">PTOptimizer</a> allows users to define
<a href="Horizontal_control_points.html" title="Horizontal control points">horizontal control points</a>, <a href="Vertical_control_points.html" title="Vertical control points">vertical control points</a> and <a href="Straight_line_control_points.html" title="Straight line control points">straight line control points</a>.
These have various uses, but mainly they are good for Leveling a Finished Panorama<a class="external" href="http://wiki.panotools.org/Leveling_a_Finished_Panorama">[*]</a> and
<a href="Perspective_correction.html" title="Perspective correction">perspective correction</a>.
</p>
<h2><span class="mw-headline" id="Historical_note">Historical note</span></h2>
<p>Before PTPicker<a class="external" href="http://wiki.panotools.org/PTPicker">[*]</a>, the GUI front-ends<a class="external" href="http://wiki.panotools.org/GUI_front-ends">[*]</a> and <a href="Autopano.html" title="Autopano">autopano</a>/<a href="Autopano-sift.html" title="Autopano-sift">autopano-sift</a>, control points
were set by cutting and pasting the flags below into source photos.  You were allowed up to
twenty pairs of points and twenty images - Panorama Tools would read the bar codes embedded in
the flags and generate a script for <a href="PTOptimizer.html" title="PTOptimizer">PTOptimizer</a>.
</p><p>This functionality is still available in the <i>adjust</i> menu of the Panorama Gimp plug-in<a class="external" href="http://wiki.panotools.org/Panorama_Gimp_plug-in">[*]</a>,
however the technique is extremely laborious and <b>definitely not recommended</b>.
</p><p><img alt="Barcode flags used by the original panorama tools control point picking technique" src="Flags.png" width="272" height="526" /><a class="external" href="http://wiki.panotools.org/File:Flags.png">[*]</a>
</p>



</div>								<div class="printfooter">
				Retrieved from "http://wiki.panotools.org/index.php?title=Control_points&amp;oldid=13441<a class="external" href="http://wiki.panotools.org/index.php?title=Control_points&amp;oldid=13441">[*]</a>"				</div>
												</div></div></body></html>